There are prior art absorbent sanitary articles comprising a main body, defined in general as a piece of a composite web and having a main direction of extension.
The main body has a front end portion, known to experts in the field simply as “front”, designed to be positioned, in use, in front of a user, and a rear end portion, known to experts in the field simply as “back” designed to be positioned, in use, behind the user.
The absorbent articles of known type comprise a pair of side panels or flaps, possibly comprising more parts connected to each other, which extend on opposite sides of the front end portion, in the jargon of the trade known as “front panel”, and a pair of side panels or flaps, possibly comprising more parts connected to each other, which extend on opposite sides of the rear end portion, in the jargon of the trade known as “back panel”.
The rear panels are generally provided with systems for attaching or joining to the corresponding front panel, if present, to encircle the waist of the user.
As is known, both the front panels and the rear panels are made, during the manufacture of the nappies, from webs which are cut into pieces and then connected to the main body or, more generally, during the assembly, on a layer of the composite web which will constitute the main body, feeding along a feed path.
The front or rear panels have, in general, two sides which are parallel to one another, one of which being designed to connect with the main body and the opposite one designed to engage with the corresponding rear or front panel when the nappy is worn.
In general, due to reasons of cost and wearability and convenience of the nappy, the front and rear panels are made of materials and with shapes which are different from each other and, therefore, the processes for forming the front and rear panels are generally different from each other.
Wearability requirements have led to the development of so-called “asymmetrical” panels, that is, for example, in the shape of trapezium, in particular scalene, wherein the bases comprise the above-mentioned parallel sides.
Another important requirement in these processes is to attempt not to have waste material, that is, to use all the material of the webs to obtain panels; the processes for making panels without waste material are known in the sector as “zero waste” processes.
The cutting of the webs for forming the panels in trapezoidal shapes, without waste material, generally implies that, for each web, there are panels which are correctly oriented, with reference to the position of application on the main body, and others which are not.
To overcome the above mentioned drawback, processes have been developed which comprise, in short, the rotation of those panels which are not correctly positioned or oriented relative to the web on which they must be applied. Examples of these solutions are described in patent documents EP1941853 and EP2238955.
The processes which comprise the rotation of the panels before the application to the main body have some drawbacks.
The devices which actuate these rotations are complex and expensive.
The rotation of the panels has critical aspects at the high speeds during formation of the nappies.